Olives are small fruit that grow on olive trees (Olea europaea).
Olives are very high in vitamin E and other powerful antioxidants. Studies show that they are good for the heart, and may protect against osteoporosis and cancer.
Olives are often enjoyed in salads, sandwiches, tapenade or pesto.
Olives are oval-shaped, with the average olive weighing about 3–5 grams ().
Some immature olives are green, and turn black when they ripen. Others remain green even when fully ripe.
In the Mediterranean countries, 90% of olives are used to make olive oil ().
Olives contain 115–145 calories per 100 grams, or about 59 calories for 10 olives (assuming that an average olive weighs 4 grams).
They consist of 75–80% water, 11–15% fat, 4–6% carbs and minor amounts of protein.
The table below contains information on the nutrients in olives ().
Olives contain 11–15% fat.
74% percent of this fat content is oleic acid, which is a monounsaturated fatty acid. It is the main component of olive oil.
It has been linked with several health benefits, including decreased inflammation and a reduced risk of heart disease. It may even help fight cancer (, , , ).
Bottom line: Olives are an unusual fruit because of their high fat content. The most abundant fatty acid is oleic acid, which may have several health benefits.
Olives also have a low carb content.
Only 4–6% of an olive is a made up of carbs, and this consists mostly of fiber.
In fact, fiber makes up 52–86% of the total carb content.
The net digestible carb content is therefore very low. It is only around 1.5 grams in 10 average-sized olives.
However, olives are still a relatively poor source of fiber, since 10 olives only provide about 1.5 grams.
Bottom line: Olives contain 4–6% carbs, most of which consists of fiber.
Olives are a good source of several vitamins and minerals, some of which are added during processing.
- Vitamin E: High-fat plant foods usually contain the highest amounts of this powerful antioxidant.
- Iron: Black olives are a good source of iron, which is important for the transport of oxygen in red blood cells ().
- Copper: This essential mineral is often lacking in the typical western diet. Copper deficiency may increase the risk of heart disease (, ).
- Calcium: The most abundant mineral in the body. It is essential for bone, muscle and nerve function ().
- Sodium: Most olives contain a high amount of sodium, since they are packaged in brine or saltwater.
Bottom line: Olives are a good source of vitamin E, iron, copper and calcium. They may also contain high amounts of sodium if packaged in saltwater.
Olives are rich in many plant compounds. They are particularly high in antioxidants ().
- Oleuropein: This is the most abundant antioxidant in fresh, unripe olives. It is linked with many health benefits ().
- Hydroxytyrosol: During olive ripening, oleuropein is broken down into hydroxytyrosol. It is also a powerful antioxidant (, ).
- Tyrosol: Most prevalent in olive oil, this antioxidant is not as potent as hydroxytyrosol. However, it may help prevent heart disease (, ).
- Oleonalic Acid: This antioxidant may help prevent liver damage, regulate blood fats and reduce inflammation (, ).
- Quercetin: This nutrient may lower blood pressure and improve heart health.
Bottom line: Olives are particularly rich in antioxidants, including oleuropein, hydroxytyrosol, tyrosol, oleonalic acid and quercetin.
The most common varieties of whole olives (table olives) are:
- Spanish green olives, pickled.
- Greek black olives, natural.
- California olives, ripened with oxidation and then pickled.
Because olives are very bitter, they are not usually eaten fresh. Instead, they are cured and fermented.
This process removes bitter compounds like oleuropein, which are most abundant in unripe olives.
The lowest levels of bitter compounds are found in ripe, black olives (, ).
However, there are some varieties that don't need processing and can be consumed when fully ripe.
Processing olives may take anywhere from a few days up to a few months, depending on the method used. Processing methods often rely on local traditions, which affect taste, color and texture ().
Lactic acid is also important during fermentation. It acts as a natural preservative that protects the olives from harmful bacteria.
Currently, researchers are exploring if fermented olives have probiotic effects in the body. This could lead to improved digestive health (, ).
Bottom line: Fresh olives are very bitter and usually need to be cured and fermented. This fermentation process may lead to beneficial effects on digestive health.
Olives are a staple of the Mediterranean diet. They have been associated with many health benefits, especially for heart health and cancer prevention.
Dietary antioxidants have been shown to reduce the risk of chronic diseases such as heart disease and cancer.
Olives are rich in antioxidants, with health benefits ranging from fighting inflammation to reducing the growth of unwanted microorganisms ().
One study showed that eating a pulpy residue from olives significantly increased blood levels of glutathione. This is one of the most powerful antioxidants in the body (, ).
Olives may also fight against the bacteria responsible for infections in the airway and stomach ().
Bottom line: Olives are very rich in antioxidants. They may reduce oxidative damage in the body and help fight infections caused by bacteria.
Improved Heart Health
High blood cholesterol and high blood pressure are both well-known risk factors for heart disease.
Oleic acid, the main fatty acid in olives, has been associated with improved heart health. It may regulate cholesterol levels and protect the LDL-cholesterol from oxidation (, ).
Furthermore, some studies have shown that olives and olive oil are able to reduce blood pressure (, ).
Bottom line: Olives and olive oil may help regulate cholesterol and protect LDL-cholesterol from oxidation. They may also help reduce blood pressure.
Improved Bone Health
Osteoporosis is characterized by decreased bone mass and bone quality. It can increase the risk of fractures.
The rates of osteoporosis are lower in Mediterranean countries than in other European countries, which has caused scientists to speculate that olives might be protective (, ).
Some of the plant compounds found in olives and olive oil have been shown to help prevent bone loss in animal studies (, , , ).
Human studies on this are lacking, but the animal studies and the data linking the Mediterranean diet to decreased fracture rates are promising ().
Bottom line: Olive consumption may reduce the risk of bone loss and osteoporosis, but more human studies are needed.
Olives and olive oil are commonly consumed in the Mediterranean region, where the incidence of cancer and other chronic diseases is lower than in other European or American countries ().
It is possible that eating olives may help reduce the risk of cancer.
This may be partly due to their high content of antioxidants and oleic acid. In test-tube experiments, these have been shown to be able to disrupt the life cycle of cancer cells in the breast, colon and stomach (, , , , ).
However, human studies are needed to confirm these results. At this point, it is unclear whether eating olives has any effect on cancer.
Bottom line: Olives are rich in many antioxidants, and test-tube studies indicate that they may help fight cancer. However, human studies are needed to confirm these findings.
Olives are well tolerated by most people, but they may contain high amounts of salt due to the liquid they are packed in.
While allergy to olive tree pollen is common, allergy to olives is rare.
After eating olives, sensitive individuals may experience allergic reactions in the mouth and throat ().
Olives may contain heavy metals and minerals like boron, sulphur, tin and lithium.
Consuming a high quantity of heavy metals may have harmful effects and increase the risk of cancer ().
However, the amount of these heavy metals in olives is generally well below the legal limit. They are therefore considered safe ().
Acrylamide has been linked with an increased risk of cancer in some studies, although more recent studies are questioning the connection (, ).
However, authorities recommend limiting the amount of acrylamide in food as much as possible ().
Some olive varieties may contain high amounts of acrylamide as a result of processing, especially ripe, California black olives (, , ).
Bottom line: Olives are usually well tolerated and allergy is rare. However, they may contain minor amounts of heavy metals and high amounts of salt. Some varieties may also contain acrylamide.
Olives are a savory and delicious addition to meals or appetizers.
They are low in carbs, but high in healthy fats. They have also been linked to several health benefits, including improved heart health.
Olives are very easy to incorporate into the diet, and make a great addition to a healthy, real food-based diet.